Video display terminals (VDTs) used with computers and in television sets give off propagating electromagnetic radiation composed of electric and magnetic components and an associated static electric field. Recently, the magnetic field component of this electromagnetic radiation has become the cause of public concern resulting in governmental regulation as to acceptable levels. Although others in the past have attempted to provide electromagnetic radiation detectors which measured harmful levels of energy emanating from microwave ovens and other high-power microwave devices used in domestic, industrial, medical and military applications, none of these prior devices are adapted to measure the extremely low frequency (ELF ranging from 5 to 2000 hertz) and very low frequency (VLF ranging from 2000 to 400,000 hertz) magnetic radiation which emanates from video display terminals.
Thus, an urgent need exists for a simple reliable device which can be attached to a video display terminal to warn people who work or live near video display terminals that a particular terminal emits a harmful level of low frequency magnetic radiation. Such a device should provide a low cost but foolproof method which is readily usable by lay persons to determine whether low frequency magnetic radiation leakage from a video display terminal exceeds the level proscribed by governmental standards.
It is a principal object of the present invention to provide a low cost device which is easily utilized by lay persons and is adapted to measure ELF and VLF magnetic radiation levels.
Another object of the present invention is to provide a a device adapted to indicate whether the level of magnetic radiation leakage from a video display terminal exceeds governmental standards.